Question

There are 4 bus lines between a and b and three bus lines between b and c, in hw many ways can a man travel round trip by bus from a to c by way of b if he does not want to use a bus line more than once

Answer 1

A man can travel from A to B in 4 different ways, and from B to C in 3 different ways.
By fundamental principle of counting, he can travel from A to C in (4x3) different ways.

→ Ans = 12 ways

(attached photo might help)

:)